MAS

This document is normative: every numeric field in the MAS schema carries the unit listed here. JSON values are bare numbers; the unit is fixed by this table and is not encoded per value. Tools may render values in scaled units (e.g. mm, kHz, °F) for human display, but the wire format is what this document specifies.

The ratifying specification is RFC 0001 v2 (proposals/0001-units.md). For the rationale on why MAS does not wrap values in {value, unit} objects, see that RFC.

Quick reference

Quantity	Unit	UCUM code	Typical fields
Frequency	hertz	Hz	switchingFrequency, ringing frequency, resonance
Time	second	s	dwell time, duty-cycle interval
Temperature	degree Celsius	Cel	ambientTemperature, Curie temperature, insulation class, loss-curve x-axes
Temperature difference	kelvin	K	temperature rise, thermal resistance numerator
Length	metre	m	core dimensions, gap length, winding window dims
Area	square metre	m2	effective area Ae, window area Aw
Volume	cubic metre	m3	effective volume Ve
Mass	kilogram	kg	core mass, winding mass
Current	ampere	A	DC, peak, RMS (per field name)
Voltage	volt	V	DC, peak, RMS (per field name)
Resistance	ohm	Ohm	DC resistance, AC effective
Inductance	henry	H	self, mutual, leakage
Capacitance	farad	F	inter-winding, stray
Charge	coulomb	C	partial-discharge inception
Energy	joule	J	per-cycle, stored
Power	watt	W	losses, throughput
Loss density	watt per cubic metre	W/m3	core-loss curve y-axis
Magnetic flux density	tesla	T	peak, AC, saturation
Magnetic field strength	ampere per metre	A/m	H, coercive force Hc
Magnetic flux	weber	Wb	Φ
Magnetic permeability	dimensionless (relative)	1	μᵣ; absolute μ is rarely used
Reluctance	per henry	/H	core, gap
Thermal resistance	kelvin per watt	K/W	rise per loss
Thermal conductivity	watt per metre kelvin	W/(m.K)	bobbin / potting / core property
Specific heat capacity	joule per kilogram kelvin	J/(kg.K)	thermal mass
Density (mass)	kilogram per cubic metre	kg/m3	material density
Resistivity	ohm metre	Ohm.m	wire material
Conductivity	siemens per metre	S/m	wire material (alternate to resistivity)
Angle	radian	rad	phase, mechanical angle
Plane angle (catalogue)	degree	deg	only where the catalogue source specifies degrees; document at the field
Dimensionless ratios	dimensionless	1	duty cycle, turns ratio, winding fill factor

Conventions

Temperature is Celsius

MAS uses °C for every temperature field. Rationale:

• Every ferrite datasheet, every wire enamel temperature class (IEC 60085: B = 130 °C, F = 155 °C, H = 180 °C, etc.), every Curie point, every insulation rating is published in °C.
• ISO 80000-5 explicitly accepts °C alongside K and recommends °C for "everyday temperatures."
• IEC standards in the magnetics space (60085, 60401, 62317, 63093) use °C.

Exception: temperature differences (rise above ambient, the denominator inside thermal resistance) use K. A Celsius difference and a Kelvin difference are numerically identical, but K is the SI form for differences. Field names that mean a difference (e.g. temperatureRise, K/W thermal resistance) are in K.

Length is metres

JSON values for length, area and volume are in base SI (m, m², m³). A core leg of 34.1 mm is encoded as 0.0341. Catalogue UIs typically display millimetres; that is a presentation choice, not a schema one.

RMS, peak and DC

Field names always disambiguate: rmsCurrent, peakCurrent, dcCurrent. A bare current (without a qualifier) is a documentation defect — open an issue.

Single numbers, not tolerance bands

Datasheet values are encoded as single numbers. Permeability, saturation flux density, gap length, resistivity — one nominal value per field, no {nominal, minimum, maximum} wrapper. If a future field genuinely needs a band, sibling fields (<field>Min, <field>Max) are added at that point.

Out-of-table units

If you encounter a numeric field whose unit is not covered here, that is a bug in either the spec or this document — please open an issue. Do not silently introduce a new unit in a downstream tool.

UCUM

The UCUM codes in the third column are informative, included so that downstream consumers (HL7 FHIR exporters, AAS / Industry 4.0 digital twins, IEC 61360 / CDD records) can carry MAS data lossless. They are not currently encoded in the JSON. RFC 0001 v2 §3 discusses why.